CVE-2023-45813
TorBot vulnerable to Inefficient Regular Expression Complexity in validate_link
Impact
### Summary _The torbot.modules.validators.validate_link function uses the python-validators URL validation regex. This particular regular expression has an exponential complexity which allows an attacker to cause an application crash using a well-crafted argument.._ ### Details https://github.com/DedSecInside/TorBot/blob/d2b89192379ad033ffc7044efff26e16ccc02d5a/torbot/modules/validators.py#L13 An attacker can use a well-crafted URL argument to exploit the vulnerability in the regular expression and cause a Denial of Service on the system. ### PoC I have uploaded a secret gist containing a PoC (https://gist.github.com/ikkebr/6041055314f1cfb8e65b2a1acbaae12c). By adding one special character at the end of the user argument of the URL, the regular expression will take exponentially longer to compute. For a string of size 10k, the regex will take 0.01s without the well-crafted URL and 1.3s with the well-crafted URL exploit. For a string of size 50k, the regex will take 0.03s without the well-crafted URL and 35s with the well-crafted URL exploit. For a string of size 100k, the regex will take 0.05s without the well-crafted URL and over 200s with the well-crafted URL exploit. The regular expression used in the validators library versions [0.20, 0.11] is vulnerable to this attack. Version 0.21 appears to be unaffected, but it no longer contains a single regular expression. ### Impact An attacker could exploit this vulnerability to cause a denial of service or increased resource usage.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | torbot | < 4.0.0 | 4.0.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Torbot Project | Torbot | before 4.0.0 |
| Validators Project | Validators | Versions 0.11.0, 0.20.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/DedSecInside/TorBot/commit/ef6e06bc7785355b1701d5524eb4550441086ac4
- https://github.com/DedSecInside/TorBot/security/advisories/GHSA-72qw-p7hh-m3ff
- https://github.com/advisories/GHSA-72qw-p7hh-m3ff
- https://nvd.nist.gov/vuln/detail/CVE-2023-45813
- https://gist.github.com/ikkebr/6041055314f1cfb8e65b2a1acbaae12c
- https://github.com/DedSecInside/TorBot/blob/d2b89192379ad033ffc7044efff26e16ccc02d5a/torbot/modules/validators.py#L13